Printing stencil and printing stencil holder with tensioning means



1967 K. FEIER ETAL 3,

PRINTING STENCIL AND PRINTING STENCIL HOLDER WITH TENSIONING MEANS Filed Dec. 11, 1964 Fig; 7

INVENTORS Kmit Em! and H Wgatkn'ullsz w (ww United States Patent 3,303,777 PRINTING STENCIL AND PRINTING STENCIL HOLDER WITH TENSIONING MEANS Kurt Feier, Riedliolz, Solothurn, and Hans Werthmuller, Wiler, near Utzensdorf, Switzerland, assignors to Fritz Buser AG., Wiler, near Utzensdorf, Switzerland, a corporation of Switzerland Filed Dec. 11, 1964, Ser. No. 417,687 Claims priority, application Switzerland, Dec. 13, E63, 15,369/63 2 Claims. (Cl. 101127.1)

The present invention pertains to an improved printing stencil for screen stencil printing machines as well as to an improved printing stencil assembly incorporating 'a new and improved support arrangement for the aforesaid printing stencil. The present invention is also concerned with an improved method of printing upon materials by means of the aforesaid printing stencil assembly.

Up to the present it was usual to stretch the flexible printing stencils which were used during screen stencil printing upon a closed and rigid frame. This frame, which during the printing operation together with the stencil extended directly over the rinting table and the materials or goods located thereon, prevented larger bending as well as a distortion of the aforesaid printing stencil. For this reason it is generally also necessary to lower the printing stencil together with the frame onto the material to be printed prior to printing, again raising such after passage of the scraper or wiper element. Since these movements are at least partially carried out during such time as the back cloth or printers blanket is stationary the standstill times associated with the printing operation are prolongated. Consequently, the efiieiency of the screen stencil printing apparatus or machine is limited.

Accordingly, it is a primary object of the present invention to provide an improved printing stencil and printing stencil assembly incorporating new and improved holder means which permits cutting-down on the standstill times associated with the printing operation as well as obviating the need to lower a frame unit.

A further important object of the present invention is directed to the provision of an improved holder arrangement for printing stencils enabling the latter to be used more efliciently, thereby increasing the production capacity of the screen stencil printing machine, as well as providing a saving in space by eliminating the use of a frame.

Still another noteworthy object of this invention concerns an improved method of printing upon materials enabling the printing operation to be carried out more efficiently by cutting-down on the standstill times normally occurring with screen stencil printing machines using a frame.

It is to be distinctly understood that the inventive printing stencil can also be employed with printing processes which do not work with scrapers, wipers or equivalent coloring matter or printing ink applying means.

The inventive printing stencil is characterized by the features that, the support for such printing stencil is formed by two rail members which are resistant to bending in the plane of the body of the printing stencil, each rail member being connected with a respective one of the two parallel lateral sides of the aforesaid printing stencil.

The present invention is also concerned with a printing stencil assembly arranged at a screen stencil printing machine -using such printing stencil, and which is characterized by the features that, the rail members of the printing stencil arranged in parallelism with the lateral or lengthwise sides of the machine are connected with the stationary portion of the machine via at least one respective holder, with at least the holder at one side being equipped with tension means enabling lateral displacement of the associated rail member against the pre-stress of a spring.

The inventive method of printing upon a material by means of a printing stencil comprises the steps of: holding a printing stencil at a predetermined spacing above a work table carrying the material to be printed upon, resiliently supporting one lateral side of the printing stencil to enable the latter to move laterally with respect to the lengthwise direction of the work table, successively applying a force from one lateral side of the printing stencil to the other in a direction to selectively depress finite portions of the printing stencil in a direction towards said material, in order to thereby be able to successively print upon finite portions of the material.

Other features, advantages and objects of the invention will become apparent by reference to the following detailed description and drawing in which:

FIGURE 1 schematically illustrates a cross-sectional view through a printing stencil and the screen stencil printing machine;

FIGURE 2 illustrates the printing stencil of the invention in plan view; and

FIGURE 3 is a cross-sectional view, somewhat on an enlarged scale, through a holder unit for the printing stencil depicted in FIGURE 2.

Describing now the drawing, in FIGURES l and 2 the printing stencil is designated by reference numeral 1 and incorporates a stencil body member 1a formed, by way of example, from a sieve netting or screen 1b, preferably manufactured from rustproof steel for instance. Two plates or rail members 2 are connected to the lateral sides 10 of the printing stencil 1 which extend parallel to the longitudinal axis of the screen stencil printing machine. It is to be understood that the rail members 2 possess a considerable rigidity or bending strength in the plane of the printing stencil 1. Furthermore, the connection between this printing stencil 1 and the rail members 2, which should be uninterrupted throughout the entire length, can be effected by brazing or hardsoldering, adhesive, or, if desired, by clamp means. Also, if the situation requires, a non-illustrated reinforcement can be provided at the lateral sides 1c of the printing stencil 1 extending between the rail members 2, for example in the form of flexible metal bands arranged in the plane of the aforesaid printing stencil.

As will become readily apparent by inspecting FIG- URES 1 and 3, the rail members 2 are fastened to a respective support section or member 3, each support member 3 here being shown, by way of example, as an angle plate 3a arranged at a spacing H above the printing or Work table 4. Holder means 5 and 6 are illustrated in FIGURE 2. These operably connect the associated support members 3 in adjustable position with the printing table 4. One such holder means 5 is depicted in greater detail in vertical cross-section in FIG- URE 3.

Now, by referring to FIGURE 3, it will be seen that a rail 7 rigidly connected at the printing table 4 extends in the lengthwise direction of this table. A support 8 is guided in this rail 7. Considering now the physical structure of the support 8 it will be seen that such exhibits two transversely extending guide bores 9 in which two bolts 11 are displaceable via suitable frictionless bearings 10. The bolt members 11 are connected to a holder housing 12 which carries a threaded spindle 13 extending substantially parallel to the bolt members 11. This threaded spindle 13 extends into a blind hole 14 provided at the support 8 and is threaded into a nut member 15 which is displaceable within this aforesaid blind hole, yet is secured against rotation in suitable manner- A tension spring 16 is arranged between the rear wall 14a of the blind hole 14 and the nut member 15, the initial bias or pre-stress of which can be altered by rotating the threaded spindle 13.

The holder housing 12, inturn, carries a support 18 which is displaceable through a small distance upon two bolts 17, this support 18 being adjustable in the lengthwise direction of the work table 4 by means of a spindle 19. It will also be recognized that the support member 3 is rigidly connected to this associated support 18. Moreover, FIGURE 3 further reveals that the rail member 2 is suspended in studs or plugs 20 which are preferably provided at uniform spacing from one another at the support member 3.

The holder unit 6 confronting the aforedescribed holder unit difiFers mainly from such holder unit 5 in that, in this case, the nut member 15 provided in said holder unit is rigidly connected with the support 8, so that an adjustment of the associated spindle 13 leads to a forced displacement of the holder housing 12 and thereby the support 18 in transverse or lateral direction with respect to the work table 4. Consequently, the spring 16 can be dispensed with, and furthermore, the bearings 10, in this instance, can be replaced by usual slide bearings.

The holder units 5' and 6' of FIGURE 2 differ from the holder units 5 and 6 only in that, here the support member 3 is directly connected with the corresponding holder housing 12. Thus, in this case the support 18 can be dispensed with since an adjustment in the lengthwise direction of the table 4, apart from the adjustment of the supports 8 which are normally rigidly clamped to the rails 7, is not necessary at both ends of the printing stencil 1.

Due to the displaceability of the support member 3 at the one side of the printing stencil 1 in transverse or lateral direction with respect to the work or printing table 4 in consequence of displacement of the holder housing 12 relative to the support 8, it is possible to lower the printing stencil 1 at a certain finite region of its width onto the printing or work table 4 and onto the material to be printed which is located thereon, for example in the operating zone of appropriate rollers 22, 23 (FIGURE 1). As a result, it is unnecessary to carry out a vertical positioning of the printing stencil 1 by means of a frame. Moreover, the illustrated printing stencil assembly provides the additional advantage that only that range or region of the width thereof, at which the. printing operation is momentarily carried out, is located in the direct neighborhood of the material to be printed. This is then of particular importance if the printing stencil should be employed for electrostatic printing during which an electrostatic field must be generated between such printing stencil and the printing table. Since the field in the instant situation is formed upon a finite surface region, whereas the remaining surface of the printing stencil exhibits a relatively large spacing from the lower support surfaces, practically no losses result and it is possible to maintain in the effective region a field of practically constant strength. Additionally, the spacing of the effective stencil region from the support surface, owing to the limited surface, can be more exactly controlled than if the entire stencil surface is lowered at on time.

The advantages of the described printing stencil regarding the mounting thereof should be quite apparent. In particular, there results a considerable saving in space due to face that a frame is not employed.

While there is shown and described present preferred embodiments of the invention it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practised within the scope of the following claims.

What is claimed is:

1. Printing stencil assembly for a screen stencil printing machine comprising a printing stencil incorporating a stencil body member, support means to which is attached said stencil body member, said support means comprising two rail members which are resistant to bending in the plane of said stencil body member, said stencil body member including a pair of parallel lateral sides, one such rail member connected to each lateral side, at least one holder means operably connected with each rail member, at least one of said holder means at one lateral side of said printing stencil being provided with tensioning means enabling lateral displacement of the rail member associated with said last-mentioned holder means against the pre-stress of a spring,. said last-mentioned holder means including a support provided with a blind hole, said tensioning means comprising a threaded spindle extending into said blind hole, a non-rotatable nut member mounted for axial movement disposed in said blind hole, said threaded spindle piercingly extending through said nut member, a spring member located within said blind hole and bearing against said nut member.

2. Printing stencil assembly as set forth in claim 1, further including a holder housing rotatably supporting said threaded spindle.

References Cited by the Examiner UNITED STATES PATENTS 1,419,663 6/1922 Erdle 10l--l26 1,545,926 7/1925 Rand 10l126 1,956,611 5/1934 Besocke 101l26 2,018,989 10/1935 Wulf l01126 2,114,973 4/1938 Wulf 101-426 OTHER REFERENCES Koslofr", A'.: The Art and Craft of Screen Process Printing, 1960, Bruce Pub. C0., Milwaukee. Only pp. 66 and 67. TT 273 K66a.

DAVID KLEIN, Primary Examiner. 

1. PRINTING STENCIL ASSEMBLY FOR A SCREEN STENCIL PRINTING MACHINE COMPRISING A PRINTING STENCIL INCORPORATING A STENCIL BODY MEMBER, SUPPORT MEANS TO WHICH IS ATTACHED SAID STENCIL BODY MEMBER, SAID SUPPORT MEANS COMPRISING TWO RAIL MEMBERS WHICH ARE RESISTANT TO BENDING IN THE PLANE OF SAID STENCIL BODY MEMBER, SAID STENCIL BODY MEMBER INCLUDING A PAIR OF PARALLEL LATERAL SIDES, ONE SUCH RAIL MEMBER CONNECTED TO EACH LATERAL SIDE, AT LEAST ONE HOLDER MEANS OPERABLY CONNECTED WITH EACH RAIL MEMBER, AT LEAST ONE OF SAID HOLDER MEANS AT ONE LATERAL SIDE OF SAID PRINTING STENCIL BEING PROVIDED WITH TENSIONING MEANS ENABLING LATERAL DISPLACEMENT OF THE RAIL MEMBER ASSOCIATED WITH SAID LAST-MENTIONED HOLDER MEANS AGAINST THE PRE-STRESS OF A SPRING, SAID LAST-MENTIONED HOLDER MEANS INCLUDING A SUPPORT PROVIDED WITH A BLIND HOLE, SAID TENSIONING MEANS COMPRISING A THREADED SPINDLE EXTENDING INTO SAID BLIND HOLE, A NON-ROTATABLE NUT MEMBER MOUNTED FOR AXIAL MOVEMENT DISPOSED IN SAID BLIND HOLE, SAID THREADED SPINDLE PIERCINGLY EXTENDING THROUGH SAID NUT MEMBER, A SPRING MEMBER LOCATED WITHIN SAID BLIND HOLE AND BEARING AGAINST SAID NUT MEMBER. 